Conventionally, there are often cases where a pilot hole called an “anchor bolt hole” is drilled in concrete or stone in advance of embedding a metal anchor bolt in the concrete or stone. In order to realize great pull-out resisting strength of the anchor bolt embedded in the pilot hole, it is necessary to remove dust, such as swarf, from the inside of the pilot hole in advance of embedding the anchor bolt in the pilot hole. It is also required that the work environment be considered when performing the work of drilling a hole in concrete or stone so that powder dust will not be scattered to the surroundings.
In view of the above, conventionally, a dust suction drill that removes dust at the same time as drilling a hole has been proposed (see Patent Literature 1). The dust suction drill is formed as follows: as shown in FIG. 16, two slits 29 are formed in a distal end surface 3a of a drill shaft 3, which rotates about an axis line L; and plate-shaped cutting edges 21 are inserted in the respective slits 29. The distal end surface of each cutting edge 21 is inclined to form an upward slope toward the radius center of the drill shaft 3. A dust suction hole 24 or dust suction holes 24 intended for sucking dust is/are formed in the distal end surface of the drill shaft 3, such that the dust suction hole(s) 24 is/are positioned at the side of the slits 29. A dust suction device (not shown) is connected to the dust suction hole(s) 24. When the drill shaft 3 rotates about the axis line L and the cutting edges 21 drill a hole in a drilling object, dust is generated, and the generated dust is sucked by the dust suction device through the dust suction hole(s) 24.